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An investigation of a nonspiking Ohmic contact to n-GaAs using the Si/Pd system

Published online by Cambridge University Press:  31 January 2011

L. C. Wang
Affiliation:
Department of Electrical and Computer Engineering, University of California—San Diego, La Jolla, California 92093
B. Zhang
Affiliation:
Department of Electrical and Computer Engineering, University of California—San Diego, La Jolla, California 92093
F. Fang
Affiliation:
Department of Electrical and Computer Engineering, University of California—San Diego, La Jolla, California 92093
E. D. Marshall
Affiliation:
Department of Electrical and Computer Engineering, University of California—San Diego, La Jolla, California 92093
S. S. Lau
Affiliation:
Department of Electrical and Computer Engineering, University of California—San Diego, La Jolla, California 92093
T. Sands
Affiliation:
Bell Communications Research Inc., Red Bank, New Jersey 07701
T. F. Kuech
Affiliation:
IBM, Thomas J. Watson Research Laboratory, Yorktown Heights, New York 10598
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Abstract

A low-resistance nonspiking Ohmic contact to n-GaAs is formed via solid-state reactions utilizing the Si/Pd/GaAs system. Samples with Si to Pd atomic ratios greater than 0.65 result in specific contact resistivity of the order of 10−6 Ω cm2, whereas samples with atomic ratios less than 0.65 yield higher specific contact resistivities or rectifying contacts. Rutherford backscattering spectrometry, cross-sectional transmission electron microscopy, and electron diffraction patterns show that a Pd, Si layer is in contact with GaAs with excess Si on the surface after the Ohmic formation annealing. This observation contrasts with that on a previously studied Ge/Pd/GaAs contact where Ohmic behavior is detected after transport of Ge through PdGe to the interface with GaAs. Comparing the Ge/Pd/GaAs system with the present Si/Pd/GaAs system suggests that a low barrier heterojunction between Ge and GaAs is not the primary reason for Ohmic contact behavior. Low-temperature measurements suggest that Ohmic behavior results from tunneling current transport mechanisms. A regrowth mechanism involving the formation of an n+ GaAs surface layer is proposed to explain the Ohmic contact formation.

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Articles
Copyright
Copyright © Materials Research Society 1988

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References

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